Two hundred and fifty 11-day-old chickens were randomly assigned into 5 groups and except normal control group injected with cyclophosphamide once a day for 3 successive days. At day-14-old, all chickens were vaccinated with Newcastle disease vaccine. At the same time of the first vaccination, the chickens in three experimental groups were injected respectively with epimedium polysaccharide-propolis flavone immunopotentiator (EPI) at three dosages, once a day for 3 successive days. On days 7, 14, 21 and 28 after the first vaccination, the serum antibody titer and IgG, IgM, IFN-γ and IL-6 concentrations, peripheral lymphocyte proliferation, including immune organ index on day 28, were measured. The results demonstrated that EPI at high and medium doses could significantly enhance antibody titer and IgG, IgM, IFN-γ and IL-6 concentrations, promote lymphocyte proliferation and enlarge immune organ index as compared with model control group. This indicated that EPI could effectively resist the immunosuppression.
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